[cleanup crusade] Shellcheck (#4261)

* lint libreswan module

* disable linting obsolete shell modules

* shellcheck more shell modules

* fix review; lint helper scripts

* more shellcheck

* fix SC2235 in apache.chart.sh

* shellcheck last portion of charts.d scripts

* final shellcheck; make travis blocking

* fix cppcheck

* fix indents; fix expansion

* fix local var assignments

27 files changed, 203 insertions, 150 deletions

diff --git a/.travis.yml b/.travis.yml
index 54e9f8d7fe..1074d89782 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -32,7 +32,7 @@ jobs:
       script: docker run --rm -v $(pwd)/web:/code eeacms/csslint sh -c "csslint /code/*.css" || echo "OK"
     - name: "bash"
       install: skip
-      script: docker run --rm --volume "$(pwd)":/project:ro --entrypoint sh koalaman/shellcheck-alpine:v0.5.0 -c 'for file in $(find /project/ -type f -name "*.sh" ! -path "*/makeself/*" ); do if ! shellcheck --format=gcc $file; then export FAILED=true; fi; done; if [ "$FAILED" != "" ]; then exit 1; fi' || echo "OK"
+      script: docker run --rm --volume "$(pwd)":/project:ro --entrypoint sh koalaman/shellcheck-alpine:v0.5.0 -c 'for file in $(find /project/ -type f -name "*.sh" ! -path "*/makeself/*" ); do if ! shellcheck --format=gcc $file; then export FAILED=true; fi; done; if [ "$FAILED" != "" ]; then exit 1; fi'
     - stage: "test"
       name: "C"
       install: sudo apt-get install -y libcap2-bin zlib1g-dev uuid-dev fakeroot libipmimonitoring-dev libmnl-dev libnetfilter-acct-dev
diff --git a/.travis/containerized_build.sh b/.travis/containerized_build.sh
index 8beb36d6c6..314a2ec392 100755
--- a/.travis/containerized_build.sh
+++ b/.travis/containerized_build.sh
@@ -2,6 +2,6 @@
 
 set -e
 
-docker build -t dev-image -f .travis/images/Dockerfile.$1 .
+docker build -t dev-image -f ".travis/images/Dockerfile.$1" .
 
 docker run -it -w /code dev-image ./netdata-installer.sh --dont-wait --dont-start-it --install /tmp
diff --git a/.travis/create_artifacts.sh b/.travis/create_artifacts.sh
index dacc67825d..1c1f909329 100755
--- a/.travis/create_artifacts.sh
+++ b/.travis/create_artifacts.sh
@@ -1,8 +1,9 @@
 #!/bin/bash
+# shellcheck disable=SC2230
 
 if [ ! -f .gitignore ]
 then
-  echo "Run as ./travis/$(basename $0) from top level directory of git repository"
+  echo "Run as ./travis/$(basename "$0") from top level directory of git repository"
   exit 1
 fi
 
@@ -19,6 +20,6 @@ fakeroot ./packaging/git-build
 python -c 'import os,sys,fcntl; flags = fcntl.fcntl(sys.stdout, fcntl.F_GETFL); fcntl.fcntl(sys.stdout, fcntl.F_SETFL, flags&~os.O_NONBLOCK);'
 # make self-extractor
 ./makeself/build-x86_64-static.sh
-for i in *.tar.gz; do sha512sum -b $i > $i.sha; done
-for i in *.gz.run; do sha512sum -b $i > $i.sha; done
+for i in *.tar.gz; do sha512sum -b "$i" > "$i.sha"; done
+for i in *.gz.run; do sha512sum -b "$i" > "$i.sha"; done
 ./.travis/deploy-if-have-key
diff --git a/charts.d/apache.chart.sh b/charts.d/apache.chart.sh
index 779a4026a0..84d4e1bf07 100644
--- a/charts.d/apache.chart.sh
+++ b/charts.d/apache.chart.sh
@@ -103,7 +103,10 @@ apache_get() {
 	ret=$?
 	IFS="${oIFS}"
 
-	([ $ret -ne 0 ] || [ "${#apache_response[@]}" -eq 0 ]) && return 1
+	if [ $ret -ne 0 ] || [ "${#apache_response[@]}" -eq 0 ]
+	then
+		return 1
+	fi
 
 	# the last line on the apache output is "Scoreboard"
 	# we use this label to detect that the output has a new word count
diff --git a/charts.d/cpu_apps.chart.sh b/charts.d/cpu_apps.chart.sh
index f287dba431..2d83db7bb3 100644
--- a/charts.d/cpu_apps.chart.sh
+++ b/charts.d/cpu_apps.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC2154,SC1072,SC1073,SC2009,SC2162,SC2006,SC2002,SC2086,SC1117
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
diff --git a/charts.d/libreswan.chart.sh b/charts.d/libreswan.chart.sh
index f2c4b210e5..4cfc3c3f0e 100644
--- a/charts.d/libreswan.chart.sh
+++ b/charts.d/libreswan.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC1117
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
@@ -61,7 +61,8 @@ libreswan_get() {
 	libreswan_connected_tunnels=()
 
 	# convert the ipsec command output to a shell script
-	# and source it to get the values
+        # and source it to get the values
+        # shellcheck disable=SC1090
 	source <(
 		{
 			libreswan_ipsec whack --status;
@@ -86,6 +87,7 @@ libreswan_check() {
 	require_cmd ipsec || return 1
 
 	# make sure it is libreswan
+	# shellcheck disable=SC2143
 	if [ -z "$(ipsec --version | grep -i libreswan)" ]
 	then
 	    error "ipsec command is not Libreswan. Disabling Libreswan plugin."
@@ -141,7 +143,7 @@ libreswan_update_one() {
 
 	[ -z "${id}" ] && libreswan_create_one "${name}"
 
-	uptime=$(( ${libreswan_now} - ${libreswan_established_add_time[${n}]} ))
+	uptime=$(( libreswan_now - libreswan_established_add_time[${n}] ))
 	[ ${uptime} -lt 0 ] && uptime=0
 
 		# write the result of the work.
diff --git a/charts.d/load_average.chart.sh b/charts.d/load_average.chart.sh
index 41c5c22f13..f984e57861 100644
--- a/charts.d/load_average.chart.sh
+++ b/charts.d/load_average.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC2154,SC1072,SC1073,SC2009,SC2162,SC2006,SC2002,SC2086,SC1117
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
diff --git a/charts.d/mem_apps.chart.sh b/charts.d/mem_apps.chart.sh
index 9157ba1f79..ca79f60118 100644
--- a/charts.d/mem_apps.chart.sh
+++ b/charts.d/mem_apps.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC2154,SC1072,SC1073,SC2009,SC2162,SC2006,SC2002,SC2086,SC1117
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
diff --git a/charts.d/mysql.chart.sh b/charts.d/mysql.chart.sh
index 3b64d696a9..9008643a7a 100644
--- a/charts.d/mysql.chart.sh
+++ b/charts.d/mysql.chart.sh
@@ -26,7 +26,8 @@ mysql_get() {
 	IFS=$'\t'$'\n'
 	#arr=($(run "${@}" -e "SHOW GLOBAL STATUS WHERE value REGEXP '^[0-9]';" | egrep "^(Bytes|Slow_|Que|Handl|Table|Selec|Sort_|Creat|Conne|Abort|Binlo|Threa|Innod|Qcach|Key_|Open)" ))
 	#arr=($(run "${@}" -N -e "SHOW GLOBAL STATUS;" | egrep "^(Bytes|Slow_|Que|Handl|Table|Selec|Sort_|Creat|Conne|Abort|Binlo|Threa|Innod|Qcach|Key_|Open)[^ ]+\s[0-9]" ))
-	arr=($(run "${@}" -N -e "SHOW GLOBAL STATUS;" | egrep "^(Bytes|Slow_|Que|Handl|Table|Selec|Sort_|Creat|Conne|Abort|Binlo|Threa|Innod|Qcach|Key_|Open)[^[:space:]]+[[:space:]]+[0-9]+" ))
+	# shellcheck disable=SC2207
+	arr=($(run "${@}" -N -e "SHOW GLOBAL STATUS;" | grep -E "^(Bytes|Slow_|Que|Handl|Table|Selec|Sort_|Creat|Conne|Abort|Binlo|Threa|Innod|Qcach|Key_|Open)[^[:space:]]+[[:space:]]+[0-9]+" ))
 	IFS="${oIFS}"
 
 	[ "${#arr[@]}" -lt 3 ] && return 1
@@ -56,6 +57,7 @@ mysql_check() {
 		shift
 	fi
 
+        # shellcheck disable=SC2230
 	[ -z "${mysql_cmd}" ] && mysql_cmd="$(which mysql 2>/dev/null || command -v mysql 2>/dev/null)"
 
 	if [ ${#mysql_opts[@]} -eq 0 ]
@@ -81,16 +83,18 @@ mysql_check() {
 		[ -z "${mysql_cmds[$m]}" ] && mysql_cmds[$m]="$mysql_cmd"
 		if [ -z "${mysql_cmds[$m]}" ]
 			then
-			error "cannot get mysql command for '$m'. Please set mysql_cmds[$m]='/path/to/mysql', in $confd/mysql.conf"
+			# shellcheck disable=SC2154
+			error "cannot get mysql command for '${m}'. Please set mysql_cmds[$m]='/path/to/mysql', in $confd/mysql.conf"
 		fi
 
 		mysql_get "${mysql_cmds[$m]}" ${mysql_opts[$m]}
+		# shellcheck disable=SC2181
 		if [ ! $? -eq 0 ]
 		then
 			error "cannot get global status for '$m'. Please set mysql_opts[$m]='options' to whatever needed to get connected to the mysql server, in $confd/mysql.conf"
-			unset mysql_cmds[$m]
-			unset mysql_opts[$m]
-			unset mysql_ids[$m]
+			unset "mysql_cmds[$m]"
+			unset "mysql_opts[$m]"
+			unset "mysql_ids[$m]"
 			continue
 		fi
 
@@ -99,7 +103,7 @@ mysql_check() {
 
 	if [ ${#mysql_opts[@]} -eq 0 ]
 		then
-		if [ ${unconfigured} -eq 1 -a ${tryroot} -eq 0 ]
+		if [ ${unconfigured} -eq 1 ] && [ ${tryroot} -eq 0 ]
 			then
 			mysql_check tryroot "${@}"
 			return $?
@@ -320,12 +324,13 @@ mysql_update() {
 		x="${mysql_ids[$m]}"
 		mysql_get "${mysql_cmds[$m]}" ${mysql_opts[$m]}
 
+		# shellcheck disable=SC2181
 		if [ $? -ne 0 ]
 			then
-			unset mysql_ids[$m]
-			unset mysql_opts[$m]
-			unset mysql_cmds[$m]
-			error "failed to get values for '$m', disabling it."
+			unset "mysql_ids[$m]"
+			unset "mysql_opts[$m]"
+			unset "mysql_cmds[$m]"
+			error "failed to get values for '${m}', disabling it."
 			continue
 		fi
 
diff --git a/charts.d/nginx.chart.sh b/charts.d/nginx.chart.sh
index b626be7e6c..8e7c2c6f5a 100644
--- a/charts.d/nginx.chart.sh
+++ b/charts.d/nginx.chart.sh
@@ -27,20 +27,21 @@ nginx_reading=0
 nginx_writing=0
 nginx_waiting=0
 nginx_get() {
+	# shellcheck disable=SC2207
 	nginx_response=($(run curl -Ss ${nginx_curl_opts} "${nginx_url}"))
-	[ $? -ne 0 -o "${#nginx_response[@]}" -eq 0 ] && return 1
-
-	if [ "${nginx_response[0]}" != "Active" \
-		 -o "${nginx_response[1]}" != "connections:" \
-		 -o "${nginx_response[3]}" != "server" \
-		 -o "${nginx_response[4]}" != "accepts" \
-		 -o "${nginx_response[5]}" != "handled" \
-		 -o "${nginx_response[6]}" != "requests" \
-		 -o "${nginx_response[10]}" != "Reading:" \
-		 -o "${nginx_response[12]}" != "Writing:" \
-		 -o "${nginx_response[14]}" != "Waiting:" \
-	   ]
-		then
+	# shellcheck disable=SC2181
+	if [ $? -ne 0 ] || [ "${#nginx_response[@]}" -eq 0 ]; then return 1; fi
+
+	if [ "${nginx_response[0]}" != "Active" ] ||\
+	   [ "${nginx_response[1]}" != "connections:" ] ||\
+	   [ "${nginx_response[3]}" != "server" ] ||\
+	   [ "${nginx_response[4]}" != "accepts" ] ||\
+	   [ "${nginx_response[5]}" != "handled" ] ||\
+	   [ "${nginx_response[6]}" != "requests" ] ||\
+	   [ "${nginx_response[10]}" != "Reading:" ] ||\
+	   [ "${nginx_response[12]}" != "Writing:" ] ||\
+	   [ "${nginx_response[14]}" != "Waiting:" ]
+	then
 		error "Invalid response from nginx server: ${nginx_response[*]}"
 		return 1
 	fi
@@ -53,15 +54,14 @@ nginx_get() {
 	nginx_writing="${nginx_response[13]}"
 	nginx_waiting="${nginx_response[15]}"
 
-	if [ -z "${nginx_active_connections}" \
-		-o -z "${nginx_accepts}" \
-		-o -z "${nginx_handled}" \
-		-o -z "${nginx_requests}" \
-		-o -z "${nginx_reading}" \
-		-o -z "${nginx_writing}" \
-		-o -z "${nginx_waiting}" \
-		]
-		then
+	if [ -z "${nginx_active_connections}" ] ||\
+	   [ -z "${nginx_accepts}" ] ||\
+	   [ -z "${nginx_handled}" ] ||\
+	   [ -z "${nginx_requests}" ] ||\
+	   [ -z "${nginx_reading}" ] ||\
+	   [ -z "${nginx_writing}" ] ||\
+	   [ -z "${nginx_waiting}" ]
+	then
 		error "empty values got from nginx server: ${nginx_response[*]}"
 		return 1
 	fi
@@ -73,8 +73,10 @@ nginx_get() {
 nginx_check() {
 
 	nginx_get
+	# shellcheck disable=2181
 	if [ $? -ne 0 ]
-		then
+	then
+		# shellcheck disable=SC2154
 		error "cannot find stub_status on URL '${nginx_url}'. Please set nginx_url='http://nginx.server/stub_status' in $confd/nginx.conf"
 		return 1
 	fi
diff --git a/charts.d/nut.chart.sh b/charts.d/nut.chart.sh
index 07f571bdc0..af9f63e1db 100644
--- a/charts.d/nut.chart.sh
+++ b/charts.d/nut.chart.sh
@@ -56,21 +56,23 @@ nut_check() {
 	for x in $nut_ups
 	do
 		nut_get "$x" >/dev/null
+		# shellcheck disable=SC2181
 		if [ $? -eq 0 ]
+		then
+			if [ ! -z "${nut_names[${x}]}" ]
 			then
-				if [ ! -z "${nut_names[${x}]}" ]
-				then
-					nut_ids[$x]="$( fixid "${nut_names[${x}]}" )"
-				else
- 					nut_ids[$x]="$( fixid "$x" )"
-				fi
+				nut_ids[$x]="$( fixid "${nut_names[${x}]}" )"
+			else
+				nut_ids[$x]="$( fixid "$x" )"
+			fi
 			continue
 		fi
 		error "cannot get information for NUT UPS '$x'."
 	done
 
 	if [ ${#nut_ids[@]} -eq 0 ]
-		then
+	then
+		# shellcheck disable=SC2154
 		error "Cannot find UPSes - please set nut_ups='ups_name' in $confd/nut.conf"
 		return 1
 	fi
@@ -230,7 +232,8 @@ END {
 		print \"END\"
 	}
 }"
-		[ $? -ne 0 ] && unset nut_ids[$i] && error "failed to get values for '$i', disabling it."
+		# shellcheck disable=2181
+		[ $? -ne 0 ] && unset "nut_ids[$i]" && error "failed to get values for '$i', disabling it."
 	done
 
 	[ ${#nut_ids[@]} -eq 0 ] && error "no UPSes left active." && return 1
diff --git a/charts.d/opensips.chart.sh b/charts.d/opensips.chart.sh
index ed04044def..6385717fa8 100644
--- a/charts.d/opensips.chart.sh
+++ b/charts.d/opensips.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC1117,SC2154,SC2086
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
@@ -35,8 +35,10 @@ opensips_check() {
 	fi
 
 	# check once if the command works
-	local x="$(opensips_get_stats | grep "^opensips_core_")"
-	if [ ! $? -eq 0 -o -z "$x" ]
+	local x
+	x="$(opensips_get_stats | grep "^opensips_core_")"
+	# shellcheck disable=SC2181
+	if [ ! $? -eq 0 ] || [ -z "$x" ]
 	then
 		error "cannot get global status. Please set opensips_opts='options' whatever needed to get connected to opensips server, in $confd/opensips.conf"
 		return 1
@@ -219,6 +221,7 @@ opensips_update() {
 
 	opensips_command_failed=0
 	eval "local $(opensips_get_stats)"
+	# shellcheck disable=SC2181
 	[ $? -ne 0 ] && return 1
 
 	[ $opensips_command_failed -eq 1 ] && error "failed to get values, disabling." && return 1
diff --git a/charts.d/phpfpm.chart.sh b/charts.d/phpfpm.chart.sh
index b169856b2f..ccf0eecdfd 100644
--- a/charts.d/phpfpm.chart.sh
+++ b/charts.d/phpfpm.chart.sh
@@ -37,8 +37,12 @@ phpfpm_slow_requests=0
 phpfpm_get() {
 	local opts="${1}" url="${2}"
 
+	# shellcheck disable=SC2207,2086
 	phpfpm_response=($(run curl -Ss ${opts} "${url}"))
-	[ $? -ne 0 -o "${#phpfpm_response[@]}" -eq 0 ] && return 1
+	# shellcheck disable=SC2181
+	if [ $? -ne 0 ] || [ "${#phpfpm_response[@]}" -eq 0 ]; then
+		return 1
+	fi
 
 	if [[ "${phpfpm_response[0]}" != "pool:" \
 		|| "${phpfpm_response[2]}" != "process" \
@@ -105,9 +109,11 @@ phpfpm_check() {
 	for m in "${!phpfpm_urls[@]}"
 	do
 		phpfpm_get "${phpfpm_curl_opts[$m]}" "${phpfpm_urls[$m]}"
+		# shellcheck disable=SC2181
 		if [ $? -ne 0 ]; then
-			error "cannot find status on URL '${phpfpm_url[$m]}'. Please set phpfpm_urls[$m]='http://localhost/status' in $confd/phpfpm.conf"
-			unset phpfpm_urls[$m]
+			# shellcheck disable=SC2154
+			error "cannot find status on URL '${phpfpm_urls[$m]}'. Please set phpfpm_urls[$m]='http://localhost/status' in $confd/phpfpm.conf"
+			unset "phpfpm_urls[$m]"
 			continue
 		fi
 	done
@@ -163,6 +169,7 @@ phpfpm_update() {
 	for m in "${!phpfpm_urls[@]}"
 	do
 		phpfpm_get "${phpfpm_curl_opts[$m]}" "${phpfpm_urls[$m]}"
+		# shellcheck disable=SC2181
 		if [ $? -ne 0 ]; then
 			continue
 		fi
@@ -189,7 +196,3 @@ EOF
 
 	return 0
 }
-
-phpfpm_check
-phpfpm_create
-phpfpm_update
diff --git a/charts.d/postfix.chart.sh b/charts.d/postfix.chart.sh
index 524f1b2533..e0a7727d9e 100644
--- a/charts.d/postfix.chart.sh
+++ b/charts.d/postfix.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC1117
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
@@ -22,13 +22,15 @@ postfix_check() {
 	#  - 1 to disable the chart
 
 	# try to find the postqueue executable
-	if [ -z "$postfix_postqueue" -o ! -x "$postfix_postqueue" ]
+	if [ -z "$postfix_postqueue" ] || [ ! -x "$postfix_postqueue" ]
 	then
+		# shellcheck disable=SC2230
 		postfix_postqueue="$(which postqueue 2>/dev/null || command -v postqueue 2>/dev/null)"
 	fi
 
-	if [ -z "$postfix_postqueue" -o ! -x  "$postfix_postqueue" ]
+	if [ -z "$postfix_postqueue" ] || [ ! -x  "$postfix_postqueue" ]
 	then
+		# shellcheck disable=SC2154
 		error "cannot find postqueue. Please set 'postfix_postqueue=/path/to/postqueue' in $confd/postfix.conf"
 		return 1
 	fi
@@ -68,10 +70,10 @@ postfix_update() {
 	postfix_q_emails=0
 	postfix_q_size=0
 
-	eval "$(run $postfix_postqueue -p |\
+	eval "$(run "$postfix_postqueue" -p |\
 		grep "^--" |\
 		sed -e "s/-- \([0-9]\+\) Kbytes in \([0-9]\+\) Requests.$/local postfix_q_size=\1\nlocal postfix_q_emails=\2/g" |\
-		egrep "^local postfix_q_(emails|size)=[0-9]+$")"
+		grep -E "^local postfix_q_(emails|size)=[0-9]+$")"
 
 	# write the result of the work.
 	cat <<VALUESEOF
diff --git a/charts.d/sensors.chart.sh b/charts.d/sensors.chart.sh
index 1a7a8f71c5..ded1e0bee5 100644
--- a/charts.d/sensors.chart.sh
+++ b/charts.d/sensors.chart.sh
@@ -33,13 +33,14 @@ sensors_priority=90000
 declare -A sensors_excluded=()
 
 sensors_find_all_files() {
-	find $1 -maxdepth $sensors_sys_depth -name \*_input -o -name temp 2>/dev/null
+	find "$1" -maxdepth $sensors_sys_depth -name \*_input -o -name temp 2>/dev/null
 }
 
 sensors_find_all_dirs() {
-	sensors_find_all_files $1 | while read
+	# shellcheck disable=SC2162
+	sensors_find_all_files "$1" | while read
 	do
-		dirname $REPLY
+		dirname "$REPLY"
 	done | sort -u
 }
 
@@ -50,7 +51,7 @@ sensors_check() {
 	#  - 0 to enable the chart
 	#  - 1 to disable the chart
 
-	[ -z "$( sensors_find_all_files $sensors_sys_dir )" ] && error "no sensors found in '$sensors_sys_dir'." && return 1
+	[ -z "$( sensors_find_all_files "$sensors_sys_dir" )" ] && error "no sensors found in '$sensors_sys_dir'." && return 1
 	return 0
 }
 
@@ -58,15 +59,15 @@ sensors_check_files() {
 	# we only need sensors that report a non-zero value
 	# also remove not needed sensors
 
-	local f= v= excluded=
-	for f in $*
+	local f v excluded
+	for f in "$@"
 	do
 		[ ! -f "$f" ] && continue
-		for ex in ${sensors_excluded[@]}; do
+		for ex in "${sensors_excluded[@]}"; do
 			[[ $f =~ .*$ex$ ]] && excluded='1' && break
 		done
 
-		[ "$excluded" != "1" ] && v="$( cat $f )" || v=0
+		[ "$excluded" != "1" ] && v="$( cat "$f" )" || v=0
 		v=$(( v + 1 - 1 ))
 		[ $v -ne 0 ] && echo "$f" && continue
 		excluded=
@@ -79,14 +80,15 @@ sensors_check_temp_type() {
 	# valid temp types are 1 to 6
 	# disabled sensors have the value 0
 
-	local f= t= v=
-	for f in $*
+	local f t v
+	for f in "$@"
 	do
-		t=$( echo $f | sed "s|_input$|_type|g" )
+		# shellcheck disable=SC2001
+		t=$( echo "$f" | sed "s|_input$|_type|g" )
 		[ "$f" = "$t" ] && echo "$f" && continue
 		[ ! -f "$t" ] && echo "$f" && continue
 
-		v="$( cat $t )"
+		v="$( cat "$t" )"
 		v=$(( v + 1 - 1 ))
 		[ $v -ne 0 ] && echo "$f" && continue
 
@@ -96,34 +98,34 @@ sensors_check_temp_type() {
 
 # _create is called once, to create the charts
 sensors_create() {
-	local path= dir= name= x= file= lfile= labelname= labelid= device= subsystem= id= type= mode= files= multiplier= divisor=
+	local path dir name x file lfile labelname device subsystem id type mode files multiplier divisor
 
 	# we create a script with the source of the
 	# sensors_update() function
 	# - the highest speed we can achieve -
-	[ $sensors_source_update -eq 1 ] && echo >$TMP_DIR/sensors.sh "sensors_update() {"
+	[ $sensors_source_update -eq 1 ] && echo >"$TMP_DIR/sensors.sh" "sensors_update() {"
 
-	for path in $( sensors_find_all_dirs $sensors_sys_dir | sort -u )
+	for path in $( sensors_find_all_dirs "$sensors_sys_dir" | sort -u )
 	do
-		dir=$( basename $path )
+		dir=$( basename "$path" )
 		device=
 		subsystem=
 		id=
 		type=
 		name=
 
-		[ -h $path/device ] && device=$( readlink -f $path/device )
-		[ ! -z "$device" ] && device=$( basename $device )
+		[ -h "$path/device" ] && device=$( readlink -f "$path/device" )
+		[ ! -z "$device" ] && device=$( basename "$device" )
 		[ -z "$device" ] && device="$dir"
 
-		[ -h $path/subsystem ] && subsystem=$( readlink -f $path/subsystem )
-		[ ! -z "$subsystem" ] && subsystem=$( basename $subsystem )
+		[ -h "$path/subsystem" ] && subsystem=$( readlink -f "$path/subsystem" )
+		[ ! -z "$subsystem" ] && subsystem=$( basename "$subsystem" )
 		[ -z "$subsystem" ] && subsystem="$dir"
 
-		[ -f $path/name ] && name=$( cat $path/name )
+		[ -f "$path/name" ] && name=$( cat "$path/name" )
 		[ -z "$name" ] && name="$dir"
 
-		[ -f $path/type ] && type=$( cat $path/type )
+		[ -f "$path/type" ] && type=$( cat "$path/type" )
 		[ -z "$type" ] && type="$dir"
 
 		id="$( fixid "$device.$subsystem.$dir" )"
@@ -139,66 +141,66 @@ sensors_create() {
 
 			case $mode in
 				temperature)
-					files="$( ls $path/temp*_input 2>/dev/null; ls $path/temp 2>/dev/null )"
-					files="$( sensors_check_files $files )"
-					files="$( sensors_check_temp_type $files )"
+					files="$( ls "$path"/temp*_input 2>/dev/null; ls "$path/temp" 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
+					files="$( sensors_check_temp_type "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.temp_$id '' '$name Temperature' 'Celsius' 'temperature' 'sensors.temp' line $((sensors_priority + 1)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.temp_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.temp_$id \$1\""
 					divisor=1000
 					;;
 
 				voltage)
-					files="$( ls $path/in*_input 2>/dev/null )"
-					files="$( sensors_check_files $files )"
+					files="$( ls "$path"/in*_input 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.volt_$id '' '$name Voltage' 'Volts' 'voltage' 'sensors.volt' line $((sensors_priority + 2)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.volt_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.volt_$id \$1\""
 					divisor=1000
 					;;
 
 				current)
-					files="$( ls $path/curr*_input 2>/dev/null )"
-					files="$( sensors_check_files $files )"
+					files="$( ls "$path"/curr*_input 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.curr_$id '' '$name Current' 'Ampere' 'current' 'sensors.curr' line $((sensors_priority + 3)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.curr_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.curr_$id \$1\""
 					divisor=1000
 					;;
 
 				power)
-					files="$( ls $path/power*_input 2>/dev/null )"
-					files="$( sensors_check_files $files )"
+					files="$( ls "$path"/power*_input 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.power_$id '' '$name Power' 'Watt' 'power' 'sensors.power' line $((sensors_priority + 4)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.power_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.power_$id \$1\""
 					divisor=1000000
 					;;
 
 				fans)
-					files="$( ls $path/fan*_input 2>/dev/null )"
-					files="$( sensors_check_files $files )"
+					files="$( ls "$path"/fan*_input 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.fan_$id '' '$name Fans Speed' 'Rotations / Minute' 'fans' 'sensors.fans' line $((sensors_priority + 5)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.fan_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.fan_$id \$1\""
 					;;
 
 				energy)
-					files="$( ls $path/energy*_input 2>/dev/null )"
-					files="$( sensors_check_files $files )"
+					files="$( ls "$path"/energy*_input 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.energy_$id '' '$name Energy' 'Joule' 'energy' 'sensors.energy' areastack $((sensors_priority + 6)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.energy_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.energy_$id \$1\""
 					algorithm="incremental"
 					divisor=1000000
 					;;
 
 				humidity)
-					files="$( ls $path/humidity*_input 2>/dev/null )"
-					files="$( sensors_check_files $files )"
+					files="$( ls "$path"/humidity*_input 2>/dev/null )"
+					files="$( sensors_check_files "$files" )"
 					[ -z "$files" ] && continue
 					echo "CHART sensors.humidity_$id '' '$name Humidity' 'Percent' 'humidity' 'sensors.humidity' line $((sensors_priority + 7)) $sensors_update_every"
-					echo >>$TMP_DIR/sensors.sh "echo \"BEGIN sensors.humidity_$id \$1\""
+					echo >>"$TMP_DIR/sensors.sh" "echo \"BEGIN sensors.humidity_$id \$1\""
 					divisor=1000
 					;;
 
@@ -211,26 +213,27 @@ sensors_create() {
 			do
 				file="$x"
 				fid="$( fixid "$file" )"
-				lfile="$( basename $file | sed "s|_input$|_label|g" )"
-				labelname="$( basename $file | sed "s|_input$||g" )"
+				lfile="$( basename "$file" | sed "s|_input$|_label|g" )"
+				labelname="$( basename "$file" | sed "s|_input$||g" )"
 
-				if [ ! "$path/$lfile" = "$file" -a -f "$path/$lfile" ]
-					then
+				if [ ! "$path/$lfile" = "$file" ] && [ -f "$path/$lfile" ]
+				then
 					labelname="$( cat "$path/$lfile" )"
 				fi
 
 				echo "DIMENSION $fid '$labelname' $algorithm $multiplier $divisor"
-				echo >>$TMP_DIR/sensors.sh "echo \"SET $fid = \"\$(< $file )"
+				echo >>"$TMP_DIR/sensors.sh" "echo \"SET $fid = \"\$(< $file )"
 			done
 
-			echo >>$TMP_DIR/sensors.sh "echo END"
+			echo >>"$TMP_DIR/sensors.sh" "echo END"
 		done
 	done
 
-	[ $sensors_source_update -eq 1 ] && echo >>$TMP_DIR/sensors.sh "}"
+	[ $sensors_source_update -eq 1 ] && echo >>"$TMP_DIR/sensors.sh" "}"
 
 	# ok, load the function sensors_update() we created
-	[ $sensors_source_update -eq 1 ] && . $TMP_DIR/sensors.sh
+	# shellcheck source=/dev/null
+	[ $sensors_source_update -eq 1 ] && . "$TMP_DIR/sensors.sh"
 
 	return 0
 }
@@ -244,7 +247,8 @@ sensors_update() {
 	# for each dimension
 	# remember: KEEP IT SIMPLE AND SHORT
 
-	[ $sensors_source_update -eq 0 ] && . $TMP_DIR/sensors.sh $1
+	# shellcheck source=/dev/null
+	[ $sensors_source_update -eq 0 ] && . "$TMP_DIR/sensors.sh" "$1"
 
 	return 0
 }
diff --git a/charts.d/squid.chart.sh b/charts.d/squid.chart.sh
index 7a3a4f7941..aaa58fed08 100644
--- a/charts.d/squid.chart.sh
+++ b/charts.d/squid.chart.sh
@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+# shellcheck shell=bash disable=SC2154
 # no need for shebang - this file is loaded from charts.d.plugin
 # SPDX-License-Identifier: GPL-3.0+
 
@@ -10,13 +10,12 @@
 squid_host=
 squid_port=
 squid_url=
-squid_timeout=2
 squid_update_every=2
 squid_priority=60000
 
 squid_get_stats_internal() {
 	local host="$1" port="$2" url="$3"
-	run squidclient -h $host -p $port $url
+	run squidclient -h "$host" -p "$port" "$url"
 }